WO2024225097A1 - Electrochromic element, method for manufacturing same, and apparatus using said electrochromic element - Google Patents

Abstract

The present disclosure provides an EC element in which a separator 4 bisects the space between electrodes 2a and 2b, and EC layers 3a and 3b demarcated by the separator 4 each contain an EC compound, wherein the thermal expansion coefficient of the separator 4 is lower than the thermal expansion coefficient of the electrodes 2a and 2b, and an adhesive 5 for bonding the separator 4 and the electrodes 2a and 2b is acrylic, whereby the separator is provided without being wrinkled.

Description

Electrochromic element, its manufacturing method, and device using said electrochromic element

The present invention relates to an electrochromic element, a method for manufacturing the same, and a device using the electrochromic element.

An electrochromic (hereinafter sometimes referred to as "EC") element is an active optical element that has a pair of electrodes and an EC layer disposed between the electrodes, and adjusts the hue and light quantity in the visible light band by applying a voltage between the pair of electrodes to oxidize or reduce a compound in the EC layer.

Up until now, EC elements have been gradually used as light-control windows in homes and aircraft, but in recent years, growing demand for environmentally friendly windows has created a demand for the development of light-control windows that are larger in area and consume less power while maintaining the performance of conventional elements.

Firstly, EC elements using organic EC compounds have the characteristics of a wide range of light intensity adjustment and relatively easy color design. Furthermore, when considering coloring efficiency (the amount of optical density change divided by the required amount of charge), it is preferable that the pair of electrodes contains a complementary electrochemically active anodic material and an electrochemically active cathodic material, both of which have EC properties.

Furthermore, to achieve a high-speed response, it is necessary for a large amount of organic EC compound to react on the electrode surface per unit time, and therefore it is preferable to configure the EC layer as a solution or gel so that the organic EC compound can move freely inside the EC layer. However, when such a configuration is adopted, the anodic and cathodic organic EC compounds that react at a pair of electrodes undergo charge exchange (side reaction) inside the EC layer and relax to a neutral state. Therefore, it is necessary to continuously apply electricity to maintain the optical density, which has been an obstacle to reducing the power consumption of complementary organic EC elements.

U.S. Pat. No. 3,453,038 discloses an element structure in which a selectively permeable membrane that is permeable to electrolyte ions but not to the reactant molecules of an EC compound is installed using a gasket in a complementary organic EC element, thereby avoiding side reactions between reactants generated at a pair of electrodes.

In addition, JP 2018-177605 A discloses a double-glazing structure in which an intermediate film with a lower thermal expansion coefficient than the base material (glass substrate) is bonded to the base material via a spacer member using an adhesive and a primary sealant.

U.S. Pat. No. 3,453,038 JP 2018-177605 A

The invention disclosed in Patent Document 1 has a structure in which the selectively permeable membrane is installed using a gasket, so when applied to an EC element, the element process may be limited. Furthermore, Patent Document 2 has a structure that can only be achieved with insulating glass, where the gap between the substrate and the interlayer is several millimeters, so it cannot be used in EC elements where the gap is several tens of microns.

In an EC element in which the EC layer is divided into two by a separator, if the thermal expansion coefficient of the separator is smaller than that of the electrodes, there is a risk that the separator may wrinkle or sag when subjected to a heating process during manufacturing, or that the separator may peel off from the electrodes.

The present invention was made in consideration of the above problems, and aims to provide a configuration in which, in an EC element having a separator in an EC layer with a smaller thermal expansion coefficient than the substrate, the separator can be stretched without wrinkling or sagging.

An electrochromic device according to one embodiment of the present invention includes a first electrode, a second electrode, a separator dividing a gap between the first electrode and the second electrode, a first electrochromic layer disposed between the first electrode and the separator and including at least one electrochromic compound, and a second electrochromic layer disposed between the second electrode and the separator and including at least one electrochromic compound,
the separator has a thermal expansion coefficient smaller than that of the first electrode and the second electrode;
The first electrode and the separator, and the second electrode and the separator are bonded to each other via an acrylic adhesive.

The method for producing an electrochromic element of the present invention further comprises the steps of:
The first electrode and the separator, and the second electrode and the separator are bonded together via the acrylic adhesive, and after the acrylic adhesive is cured, a heat treatment is performed.

The present invention makes it possible to realize an EC element with high display quality, which has no wrinkles or sagging in the separator that divides the EC layer, and which achieves both excellent transparency in the neutral state and low power consumption even when made into a complementary type.

1 is a schematic cross-sectional view in a thickness direction showing a configuration of one embodiment of an EC element of the present invention. 1 is a schematic cross-sectional view in the thickness direction showing an example of a seal arrangement of an EC element of the present invention. 1 is a schematic cross-sectional view in the thickness direction showing an example of a seal arrangement of an EC element of the present invention. 1 is a schematic cross-sectional view in the thickness direction showing an example of a seal arrangement of an EC element of the present invention. FIG. 2 is a schematic diagram showing an example of a driving device including an EC element according to an embodiment of the present invention. 1 is a schematic diagram of an example of an imaging device in which an optical filter is disposed in a lens unit. 1 is a schematic diagram of an example of an imaging device in which an optical filter is disposed in the imaging device; FIG. 1 is a schematic diagram showing a window using an EC device according to an embodiment of the present invention. 1 is a schematic cross-sectional view in a thickness direction showing a window using an EC element according to an embodiment of the present invention.

The electrochromic element of the present invention is an EC element in which the gap between the electrodes is divided into two by a separator, and a pair of electrochromic layers are sandwiched between the separator. In the EC element of the present invention, each of the pair of EC layers contains at least one electrochromic compound, and the separator and the electrodes are bonded with an acrylic adhesive, so that the separator is positioned in the EC element without wrinkles or sagging, resulting in an EC element with high display quality.

Below, a preferred embodiment of the configuration of the electrochromic element according to the present invention will be described in detail with reference to the drawings. However, unless otherwise specified, the configuration, relative arrangement, etc. described in this embodiment are not intended to limit the scope of the present invention.

(EC element)
The configuration of the EC element of the present invention will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing one embodiment of the EC element 7 of the present invention. In FIG. 1, 1a and 1b are a pair of substrates, and a pair of electrodes 2a and 2b are formed on one side of the substrate, on the inside of the element. 4 is a separator, and 5 is an adhesive that bonds the electrodes 2a and 2b on the substrates 1a and 1b to the separator 4. EC layers 3a and 3b are arranged in a pair of spaces partitioned by the electrodes 2a and 2b, the separator 4, and the adhesive 5, and a seal 6 is installed around the outer periphery of the element. Hereinafter, for convenience, the substrate 1a will be referred to as the first substrate, the substrate 1b as the second substrate, the electrode 2a as the first electrode, the electrode 2b as the second electrode, the EC layer 3a as the first EC layer, and the EC layer 3b as the second EC layer.

Next, we will provide a detailed explanation of the components that make up the EC element of the present invention.

The pair of substrates 1a, 1b are required to be made of an electrical insulator such as glass or resin, and to have high transparency, excellent heat resistance, and high chemical stability. As glass, optical glass, quartz glass, white plate glass, blue plate glass, borosilicate glass, alkali-free glass, chemically strengthened glass, etc. can be used, and alkali-free glass is particularly suitable from the standpoint of transparency and durability. As resin, polycarbonate (PC), acrylic (PMMA), polyethylene terephthalate (PET), transparent polyimide (PI), etc. can be used. Furthermore, it is suitable to use resins with a hard coat layer formed on the surface to improve scratch resistance.

The pair of electrodes 2a, 2b are made of a transparent conductive material, such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide (NESA), indium zinc oxide (IZO), graphene, etc. Also suitable are conductive polymers whose conductivity has been improved by doping, such as polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, and complexes of polyethylenedioxythiophene (PEDOT) and polystyrenesulfonic acid.

The pair of EC layers 3a, 3b is preferably a solution in which an EC compound is dissolved in an organic solvent, or a gel, and may contain an electrolyte. In addition, they may have a spacer that has the function of defining the distance between the electrodes 2a, 2b and the separator 4. The spacer may be made of an inorganic material such as silica beads or glass fiber, or an organic material such as polydivinylbenzene, polyimide, polytetrafluoroethylene, fluororubber, or epoxy resin.

The EC layers 3a and 3b can be formed by injecting a liquid containing an EC compound prepared in advance into the gap between the pair of electrodes 2a and 2b and the separator 4 using a vacuum injection method, air injection method, meniscus method, etc., or by dripping a liquid containing an EC compound using the ODF method and then laminating it with the separator 4, or by coating the pair of electrodes 2a and 2b with blade coating, bar coating, slit die coating, etc., and then laminating it with the separator 4.

The EC compound is preferably an organic compound, and may be either an anodic compound that changes color from a transparent state by an oxidation reaction, or a cathodic compound that changes color from a transparent state by a reduction reaction. Both anodic and cathodic compounds may be used. The use of both an anodic and cathodic compound is preferable because it increases the coloring efficiency with respect to the current. In this specification, an element having both an anodic compound and a cathodic compound is called a complementary EC element. An anodic compound is also called an anode material, and a cathodic compound is also called a cathode material.

When a complementary EC element is driven, electrons are extracted from the EC compound by an oxidation reaction at one electrode, and electrons are received by the EC compound by a reduction reaction at the other electrode. Radical cations may be generated from neutral molecules by an oxidation reaction. Radical anions may also be generated from neutral molecules by a reduction reaction, or radical cations may be generated from dicationic molecules. Since the EC compound is colored at both of the pair of electrodes 2a, 2b, it is preferable to employ a complementary EC element when a large change in optical density is required during coloring.

Organic EC compounds include conductive polymers such as polythiophene and polyaniline, viologen compounds, anthraquinone compounds, oligothiophene derivatives, phenazine derivatives, and other organic low molecular weight compounds.

In the present invention, it is preferable that the first EC layer 3a contains at least one type of anodic EC compound, the second EC layer 3b contains at least one type of cathodic EC compound, and the separator 4 is a selectively permeable membrane that does not allow the EC compound to pass through but allows electrolyte ions to pass through. With this configuration, contact between the excited cathodic EC compound contained in the first EC layer 3a and the anodic EC compound contained in the second EC layer 3b is prevented, and cross-reaction (side reaction) between the two can be suppressed. As a result, low power consumption of the EC element 7 can be achieved. In this case, the EC layers 3a and 3b may be made of exactly the same material. The complementary type will be specifically described below.

When the EC layers 3a and 3b contain multiple types of EC compounds, it is preferable that the difference in redox potential of the EC compounds is small. When multiple types of EC compounds are present, the anodic and cathodic compounds may be combined to have four or more types of EC compounds. The EC element of the present invention may have five or more types of EC compounds. When multiple types of EC compounds are present, the redox potential of the multiple anode materials may be within 60 mV, and the redox potential of the multiple cathode materials may be within 60 mV. When multiple types of EC compounds are present, they may include a compound having an absorption peak from 400 nm to 500 nm, a compound having an absorption peak from 500 nm to 650 nm, and a compound having an absorption peak at 650 nm or more. The absorption peak refers to a peak with a half-width of 20 nm or more. In addition, the state of the material when absorbing light may be an oxidized state, a reduced state, or a neutral state.

The electrolyte is not limited as long as it is an ion-dissociating salt and has good solubility in a solvent and high compatibility with a solid electrolyte. Among them, an electrolyte having electron donating properties is preferable. These electrolytes can also be called supporting electrolytes. Examples of the electrolyte include inorganic ion salts such as various alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, and cyclic quaternary ammonium salts. Specifically, LiClO ₄ , LiSCN, LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiPF ₆ , LiI, NaI, NaSCN, NaClO ₄ , NaBF ₄ , NaAsF _{6 ,} KSCN, _{KCl , etc. , alkali metal salts of Li , Na , K , etc .; 4} NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (n-C ₄ H ₉ ) ₄ NClO ammonium salts such as quaternary ammonium salts of _{ammonium phosphate} , etc. and cyclic quaternary ammonium salts.

The solvent for dissolving the EC compound and electrolyte is not particularly limited as long as it can dissolve the EC compound and electrolyte, but it is preferable to use a solvent that has polarity. Specific examples include water and organic polar solvents such as methanol, ethanol, propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, γ-butyrolactone, γ-valerolactone, sulfolane, dimethylformamide, dimethoxyethane, tetrahydrofuran, acetonitrile, propionitrile, 3-methoxypropionitrile, benzonitrile, dimethylacetamide, methylpyrrolidinone, and dioxolane.

The EC layers 3a and 3b may further contain a polymer matrix, a gelling agent, and a cross-linking agent. In this case, the EC layers 3a and 3b may be converted from a highly viscous liquid into a gel (physical gel) by adding only a polymer, or may be converted into a gel (chemical gel) by adding a cross-linking agent to a polymer matrix. Examples of polymers include polyacrylonitrile, carboxymethylcellulose, pullulan-based polymers, polyvinyl chloride, polyethylene oxide, polypropylene oxide, polyurethane, polyacrylate, polymethacrylate, polyamide, polyacrylamide, polyester, polyvinylpyridine, Nafion (registered trademark), etc.

If the separator 4 is a selectively permeable membrane that is impermeable to EC compounds but permeable to electrolyte ions, it is preferable that it is made of nanofibers. In addition, to ensure transparency in the visible light region, it is particularly preferable to use nanocellulose (cellulose nanofiber, hereinafter sometimes referred to as "CNF") with a fiber diameter of 10 nm or less.

The thermal expansion coefficient of the separator 4 made of nanofibers is about 0.1×10 ⁻⁶ K ⁻¹ , which is one to two orders of magnitude smaller than that of ITO that is normally used for the electrodes 2a and 2b. Similarly, glass, PET film, and the like used for the substrates 1a and 1b on which the electrodes 2a and 2b are formed also have a thermal expansion coefficient one to two orders of magnitude larger than that of the separator 4. Therefore, unless an appropriate bonding means is used, the difference in the thermal expansion coefficients may cause the separator 4 of the manufactured EC element to sag or wrinkle, or peel off from the electrodes 2a and 2b.

The adhesive 5 connects the separator 4 and the pair of electrodes 2a, 2b, and has the function of stretching the separator 4, which is a thin film of several tens of microns, without wrinkles or sagging, and maintaining a constant gap between them. In addition, since it comes into direct contact with the electrochemically active EC layers 3a, 3b, it is required that it is non-reactive with the EC compound and has low affinity with the solvent that dissolves the EC compound. For this reason, an acrylic adhesive is used as the adhesive 5, which has good adhesion to the electrodes and is easy to relieve internal stress. A UV-curable acrylic adhesive, particularly a one-liquid solventless acrylic adhesive, is more preferable. It is preferable to apply a heat treatment to the UV-curable acrylic adhesive after curing it with UV light.

The seal 6 is preferably made of a material that is chemically stable and impermeable to gases and liquids. Examples include inorganic materials such as glass frit, and organic materials such as epoxy resin.

FIGS. 2A to 2C are schematic cross-sectional views showing examples of seal arrangements for the EC element of the present invention, showing one side of a thickness direction cross section. FIG. 2A shows an example where the seal 6 is arranged on the outside of the adhesive 5 within the substrate plane, FIG. 2B shows an example where the seal 6 is arranged outside the adhesive 5 outside the substrate plane, i.e., on the side of the element, and FIG. 2C is similar to FIG. 2B, but shows an example where one of the substrates is made larger and arranged on the substrate plane. These can be appropriately selected based on the thickness of the substrate, the required performance of the seal 6, ease of process, etc.

In the above embodiment, an example was given in which the EC element is a complementary type and the separator 4 is a selectively permeable membrane, but the present invention is not limited to this configuration and is preferably applied to an EC element that uses a separator 4 with a smaller thermal expansion coefficient than the electrodes 2a and 2b.

(Applications of EC elements)
The EC element according to the present invention can be used in optical filters, lens units, imaging devices, window materials, and the like.

<Optical filter>
The optical filter according to this embodiment includes an EC element and an active element connected to the EC element. The active element drives the EC element and adjusts the amount of light passing through the EC element. The active element may be, for example, a transistor. The transistor may have an oxide semiconductor such as InGaZnO in an active region.

The optical filter according to this embodiment has an EC element according to the present invention and a driving device connected to the EC element. FIG. 3 is a schematic diagram showing an example of a driving device 20 for an EC element and an EC element 7 driven by the driving device 20. The driving device 20 according to this embodiment has a driving power supply 8, a resistance switch 9, and a controller 10.

The driving power supply 8 applies to the EC element 7 a voltage necessary for the EC material contained in the EC layer to cause an electrochemical reaction. It is preferable that the driving voltage is a constant voltage. This is because when the EC material is composed of multiple types of materials, the absorption spectrum may change due to differences in the redox potential differences and molar absorption coefficients of the materials, so a constant voltage is preferable. The driving power supply 8 starts applying voltage or maintains the applied state by a signal from the controller 10, and the constant voltage application state is maintained during the period when the light transmittance of the EC element 7 is controlled.

The controller 10 controls the transmittance of the EC element 7 in a manner suited to the EC element 7 being used. Specifically, this can involve inputting predefined conditions to the EC element 7 for the desired transmittance setting, or comparing the transmittance setting with the transmittance of the EC element 7 and selecting and inputting conditions that match the setting. Parameters that can be changed include voltage, current, and duty ratio. The controller 10 can change the color density of the EC element 7 by changing the voltage, current, or duty ratio.

In this embodiment, known means can be used to change the voltage, change the current, and modulate the pulse width. Pulse width modulation can also be performed as follows.

The resistance switch 9 switches between resistor R1 (not shown) and resistor R2, which is larger than resistor R1, and connects them in series in a closed circuit including the drive power source 8 and the EC element 7. The resistance value of resistor R1 is preferably smaller than the largest impedance of the element closed circuit, and is preferably 10 Ω or less. The resistance value of resistor R2 is preferably larger than the largest impedance of the element closed circuit, and is preferably 1 MΩ or more. Resistor R2 may be air. In this case, strictly speaking the closed circuit becomes an open circuit, but it can be considered as a closed circuit by regarding the air as resistor R2.

The controller 10 sends a switching signal to the resistor switch 9 to control the switching of resistors R1 and R2, but it is also possible to generate a PWM signal using a comparator or the like without using a resistor switch.

<Lens unit>
The lens unit according to the present embodiment includes an imaging optical system having a plurality of lenses and an optical filter having an EC element according to the present invention. The optical filter may be provided either between the plurality of lenses or outside the lens. The optical filter is preferably provided on the optical axis of the lens.

<Imaging device>
The imaging device of this embodiment has an optical filter and a light receiving element that receives light that has passed through the optical filter. Specific examples of imaging devices include cameras, video cameras, and mobile phones with cameras. The imaging device may be in a form in which a main body having a light receiving element and a lens unit having a lens can be separated. In this case, when the imaging device can be separated into a main body and a lens unit, the present invention also includes a form in which an optical filter separate from the imaging device is used during imaging. In this case, the optical filter may be disposed outside the lens unit, between the lens unit and the light receiving element, between multiple lenses (when the lens unit has multiple lenses), and the like.

FIG. 4A is a schematic diagram of an example of an imaging device in which an optical filter is disposed in a lens unit, and FIG. 4B is a schematic diagram of an example of an imaging device in which an optical filter is disposed in the imaging device.

The imaging device 100 is an imaging device having a lens unit 102 and an imaging unit 103. The lens unit 102 has an optical filter 101 and an imaging optical system having a plurality of lenses or a lens group. The optical filter 101 is the optical filter of the present embodiment described above.

Lens unit 102, for example, in FIG. 4A, represents a rear-focus zoom lens in which focusing is performed behind the aperture. It has four lens groups, in order from the object side: a first lens group 104 with positive refractive power, a second lens group 105 with negative refractive power, a third lens group 106 with positive refractive power, and a fourth lens group 107 with positive refractive power. Magnification is changed by changing the distance between second lens group 105 and third lens group 106, and focusing is performed by moving some of the lens groups in fourth lens group 107.

The lens unit 102, for example, has an aperture stop 108 between the second lens group 105 and the third lens group 106, and also has an optical filter 101 between the third lens group 106 and the fourth lens group 107. The lens unit is arranged so that light passing through each of the lens groups 104 to 107, the aperture stop 108, and the optical filter 101 passes through, and the amount of light can be adjusted using the aperture stop 108 and the optical filter 101. The lens unit 102 is detachably connected to the imaging unit 103 via a mount member (not shown).

In this embodiment, the optical filter 101 is disposed between the third lens group 106 and the fourth lens group 107 in the lens unit 102, but the imaging device 100 is not limited to this configuration. For example, the optical filter 101 may be disposed either in front of (on the subject side) or behind (on the imaging unit 103 side) the aperture stop 108, or in front of, behind, or between any of the first to fourth lens groups 104 to 107. Placing the optical filter 101 at a position where light converges has the advantage of making the area of the optical filter 101 smaller.

Furthermore, the configuration of the lens unit 102 is not limited to the above configuration, and can be selected as appropriate. For example, in addition to the rear focus type, it can be an inner focus type in which focusing is performed in front of the aperture, or other types. Furthermore, in addition to zoom lenses, special lenses such as fisheye lenses and macro lenses can also be selected as appropriate.

The imaging unit 103 has a glass block 109 and a light receiving element 110. The glass block 109 is a glass block such as a low-pass filter, face plate, or color filter. The light receiving element 110 is a sensor unit that receives light that has passed through the lens unit, and an imaging element such as a CCD or CMOS can be used. It may also be an optical sensor such as a photodiode, and any device that acquires and outputs information on the intensity or wavelength of light can be used as appropriate.

When the optical filter 101 is incorporated in the lens unit 102 as shown in FIG. 4A, the driving device may be disposed inside the lens unit 102 or outside the lens unit 102. When disposed outside the lens unit 102, the EC element in the lens unit 102 is connected to the driving device through wiring to control the driving.

Furthermore, in the configuration of the imaging device 100 described above, the optical filter 101 is disposed inside the lens unit 102. However, the present invention is not limited to this configuration, and it is sufficient that the optical filter 101 is disposed at an appropriate location inside the imaging device 100, and the light receiving element 110 is disposed so as to receive light that has passed through the optical filter 101.

For example, as shown in FIG. 4B, the imaging unit 103 may have the optical filter 101. FIG. 4B is a diagram for explaining the configuration of another example of the imaging device of this embodiment, and is a schematic diagram of the configuration of an imaging device having the optical filter 101 in the imaging unit 103. In FIG. 4B, for example, the optical filter 101 is disposed immediately before the light receiving element 110. When the imaging device itself has the optical filter 101 built in, the connected lens unit 102 itself does not need to have the optical filter 101, so it is possible to configure a dimmable imaging device using an existing lens unit 102.

The imaging device 100 of this embodiment can be applied to products that have a combination of light intensity adjustment and a light receiving element. For example, it can be used in cameras, digital cameras, video cameras, and digital video cameras, and can also be applied to products that have built-in imaging devices, such as mobile phones, smartphones, PCs, and tablets.

According to the imaging device 100 of this embodiment, the optical filter 101 is used as a dimming component, making it possible to appropriately adjust the dimming amount with a single filter, which has the advantages of reducing the number of components and saving space.

<Windows>
The window according to the present embodiment includes an EC element and an active element connected to the EC element. The active element is an element that drives the EC element and adjusts the amount of light passing through the EC element. The active element may be, for example, a transistor. The transistor may have an oxide semiconductor such as InGaZnO in an active region. The window according to the present embodiment may also be called a variable transmittance window.

FIG. 5A is an overview diagram showing a light control window as a window material using the EC element of the present invention, and FIG. 5B is a schematic cross-sectional diagram in the thickness direction of the center part (X-X') of FIG. 5A. The light control window 111 of this embodiment is composed of an EC element 7 (optical filter), a transparent plate 113 that holds it, and a frame 112 that surrounds and integrates the whole. The EC element 7 of this embodiment has the configuration shown in FIG. 1 and has a drive device (not shown), which may be integrated within the frame 112, or may be arranged outside the frame 112 and connected to the EC element 7 through wiring.

The transparent plate 113 is not particularly limited as long as it is made of a material with high light transmittance, and is preferably made of a glass material considering its use as a window. The material of the frame 112 is not important, but anything that covers at least a portion of the EC element 7 and has an integrated form may be considered as a frame. In Figures 5A and 5B, the EC element 7 is a component independent of the transparent plate 113, but for example, the substrates 1a and 1b of the EC element 7 may be considered as the transparent plate 113.

Such a light-control window can be used, for example, to adjust the amount of sunlight entering a room during the day. Since it can be used to adjust not only the amount of sunlight but also the amount of heat, it can be used to control the brightness and temperature inside a room. It can also be used as a shutter to block the view from outside into the room. In addition to glass windows for buildings, such light-control windows can also be used for windows in vehicles such as cars, trains, airplanes, and ships.

In this way, the EC element of the present invention can be used in optical filters, lens units, imaging devices, window materials, etc.

Also, by providing a reflective member on one of the light paths of the EC element, it can be made into an electrochromic mirror. The EC mirror may be provided in an automobile as an anti-glare mirror. The EC mirror can be constructed by having an EC element and a reflective member disposed inside or outside the EC element. Having a reflective member inside means that the electrodes of the EC element are reflective. Having a reflective member outside means that a reflective member is provided in contact with the electrodes of the EC element or via another transparent member.

Example 1
An electrode substrate was prepared by forming an ITO electrode with a sheet resistance of 10 Ω/□ on a non-alkali glass substrate ("OA-11" manufactured by Nippon Electric Glass Co., Ltd.). The electrode substrate and a separator with a thickness of 20 μm and made of nanocellulose with a fiber diameter of 2 to 4 nm measured by AFM observation were bonded to the electrode with an adhesive so that the gap between the separator and the electrode was 30 μm. The adhesive used and its curing conditions are shown below.

[Adhesive and curing conditions]
Acrylic adhesive (UV-curable, one-component, solvent-free type)
ThreeBond's "3035B": UV irradiation process at 3000 mJ/ ^cm2 at a wavelength of 365 nm, followed by a heating process at 80°C for 30 minutes Kyoritsu Chemical's "8840": UV irradiation process at 6000 mJ/ ^cm2 at a wavelength of 365 nm, followed by a heating process at 80°C for 30 minutes Kyoritsu Chemical's "XVL-90T3": UV irradiation process at 4500 mJ/ ^cm2 at a wavelength of 365 nm, followed by a heating process at 80°C for 30 minutes Epoxy adhesive (thermosetting type)
Agilent "Torr Seal": Heating process at 60°C for 30 minutes, followed by drying process at 60°C for 120 minutes Mitsubishi Gas Chemical's "Maxive": Heating process at 80°C for 30 minutes, followed by drying process at 80°C for 120 minutes Epoxy adhesive (ultraviolet and heat curing combined type)
Mitsui Chemicals'"XMF-DU206B": UV irradiation process of 3000 mJ/ ^cm2 at a wavelength of 365 nm, followed by a heating process at 80 ° C for 30 minutes Sekisui Chemical's "E220": UV irradiation process of 1500 mJ/ ^cm2 at a wavelength of 365 nm, followed by a heating process at 80 ° C for 30 minutes

[Evaluation of separator shape]
The separator shape was visually evaluated after the ultraviolet irradiation process and the heating process for the acrylic adhesive and the ultraviolet/thermosetting epoxy adhesive, and after the drying process for the thermosetting epoxy adhesive. The evaluation criteria were as follows. The results are shown in Table 1.
◎: No sagging.
A: There is some sagging.
△: There is sagging.
×: Wrinkles present.

[Reactivity with EC layer]
Furthermore, the reactivity with the EC layer was evaluated based on the color change of the EC solution when the anodic EC compound and cathodic EC compound shown below were dissolved in propylene carbonate and brought into contact with each adhesive. The evaluation criteria were as follows. The results are shown in Table 1.
Anodic EC compound: 30 mM
3-(2-isoproxy-6-methoxyphenyl)-1,5,10-trimethyl-8-phenoxy-5,10-dihydrophenazine Cathodic EC compound: 30 mM
9,9-Dimethyl-2,7-bis(4,4,4-trifluorobutyl)-9H-cyclopenta[1,2-c:4,3-c']dipyridinium bis[bis(trifluoromethanesulfonyl)imide]
A: No color change was observed in the EC layer.
×: Color change occurred in the EC layer.

[Adhesion between separator and electrode substrate]
A peel test was carried out to peel the cured separator from the electrode substrate, and the adhesion between the separator and the substrate was relatively evaluated. The evaluation criteria were as follows. The results are shown in Table 1.
◯: No peeling was observed when a load of 100 gf/cm^2 was applied. △: Peeling was observed when a load of 100 gf/cm^2 was applied.

Epoxy adhesives, whether heat-curing or combined UV/heat-curing, did not adhere well to the separator and electrode substrate, and were reactive with the EC layer. After curing and heating, the separator showed signs of sagging and wrinkling, and the gap between the electrode surface and the separator could not be kept constant. On the other hand, acrylic adhesives showed good adhesion to the separator and did not react with the EC layer. Although slight sagging was observed in the separator after curing with UV light, this sagging was eliminated by heating.

Example 2
Two electrode substrates identical to those used in Example 1 were prepared, and an ultraviolet-curing acrylic adhesive (ThreeBond's "3035B") was drawn on one of them using a dispenser to a thickness of 30 μm. Next, an EC compound solution in which the following anodic and cathodic compounds were dissolved in propylene carbonate was dropped, and then the same separator as that used in Example 1 was vacuum-laminated. Furthermore, the same adhesive and an epoxy seal surrounding it (Mitsui Chemicals'"XMF-DU206B") were drawn on the other electrode substrate to a thickness of 30 μm using a dispenser. Next, the EC compound solution was dropped, and the electrode substrate to which the separator had been previously laminated was laminated. Thereafter, an ultraviolet irradiation process of 3000 mJ/cm ² at a wavelength of 365 nm was performed, followed by a heat treatment at 80 ° C for 30 minutes to cure the acrylic adhesive and epoxy seal, completing the EC element.

Anodic EC Compound:
3-(2-isoproxy-6-methoxyphenyl)-1,5,10-trimethyl-8-phenoxy-5,10-dihydrophenazine [27 mM]
5,10-Diisopropyl-2-(3-methoxyphenoxy)-7-methyl-5,10-dihydrophenazine [351 mM]
Cathodic EC Compound:
9,9-Dimethyl-2,7-bis(4,4,4-trifluorobutyl)-9H-cyclopenta[1,2-c:4,3-c']dipyridinium bis[bis(trifluoromethanesulfonyl)imide][284 mM]
1,1'-bis(4-tert-butyl)phenyl-3-methyl-4,4'-dipyridinium bis[bis(trifluoromethanesulfonyl)imide][94 mM]

When the obtained EC element was visually observed, the separator had a uniform and pleasing appearance with no wrinkles, sagging, tears, or peeling from the electrode substrate. When a constant voltage of 0.6 V was applied to the EC element, the light transmittance reached 1% in about 2 minutes, and uniform, high-quality coloring was observed.

Example 3
Two PET film substrates with ITO and a sheet resistance of 80Ω/□ were prepared as electrode substrates, and a UV-curable acrylic adhesive (Kyoritsu Chemical's "XVL-90T3") was applied to one of them using a dispenser to a thickness of 30 μm. The same EC compound solution as used in Example 2 was then dripped onto the other electrode substrate, and the substrate was vacuum-laminated with the same separator as used in Example 1. Furthermore, the acrylic adhesive and an epoxy seal (Sekisui Chemical's "E220") surrounding the adhesive were also applied to the other electrode substrate using a dispenser, and the same EC compound solution was then dripped onto the substrate with the separator that had been previously laminated. After that, an EC element was completed by performing an ultraviolet irradiation process at a wavelength of 365 nm and 4500 mJ/cm ² , followed by a heat treatment at 80° C. for 30 minutes.

When the obtained EC element was visually observed, the separator had a uniform and pleasing appearance with no wrinkles, sagging, tears, or peeling from the electrode substrate. When a constant voltage of 0.7 V was applied to the EC element, the light transmittance reached 1% in about 3 minutes, and uniform, high-quality coloring was observed.

(Comparative Example 1)
Two electrode substrates were prepared, the same as those used in Example 1, and a UV-curable epoxy adhesive (Mitsui Chemicals'"XMF-DU206B") was applied to one of them using a dispenser to a thickness of 30 μm. The same EC compound solution as used in Example 2 was then dripped onto the other electrode substrate, and the substrate was vacuum-laminated with a separator made of nanocellulose with a film thickness of 20 μm. Furthermore, the same adhesive and an epoxy seal (Sekisui Chemical's "E220") surrounding the adhesive were applied to the other electrode substrate using a dispenser, and the EC solution was then dripped onto the substrate with the separator that had been previously laminated. After that, an ultraviolet irradiation process of 3000 mJ/cm ² at a wavelength of 365 nm was performed, followed by a heat treatment at 80 ° C for 30 minutes to complete the EC element.

When the obtained EC element was visually observed, wrinkles were observed at the corners of the rectangular separator, and coloring was observed even in a neutral state. When a constant voltage of 0.6 V was applied to the EC element, the transmittance only decreased to about 20%, and the coloring was non-uniform.

The present invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the present invention. Therefore, in order to publicize the scope of the present invention, the following claims are appended.

This application claims priority based on Japanese Patent Application No. 2023-071494, filed on April 25, 2023, the entire contents of which are incorporated herein by reference.

2a, 2b Electrodes 3a, 3b Electrochromic layer 4 Separator 5 Adhesive 7 Electrochromic element 101 Optical filter 102 Lens unit 110 Light receiving element 100 Imaging device

Claims (12)

1. An electrochromic device comprising a first electrode, a second electrode, a separator bisecting a gap between the first electrode and the second electrode, a first electrochromic layer disposed between the first electrode and the separator and including at least one electrochromic compound, and a second electrochromic layer disposed between the second electrode and the separator and including at least one electrochromic compound,
the separator has a thermal expansion coefficient smaller than that of the first electrode and the second electrode;
An electrochromic element, characterized in that the first electrode and the separator, and the second electrode and the separator, are bonded to each other via an acrylic adhesive. The electrochromic element of claim 1, characterized in that the first electrochromic layer contains at least one cathodic electrochromic compound, and the second electrochromic layer contains at least one anodic electrochromic compound. The electrochromic element according to claim 1 or 2, characterized in that the separator is made of nanofibers. The electrochromic element according to claim 3, characterized in that the nanofibers are made of nanocellulose. The electrochromic element according to claim 4, characterized in that the separator has an average fiber diameter of 10 nm or less. An electrochromic element according to any one of claims 1 to 5, characterized in that the acrylic adhesive is an ultraviolet-curing adhesive. An optical filter comprising an electrochromic element according to any one of claims 1 to 6 and a transistor connected to the electrochromic element. A lens unit comprising the optical filter according to claim 7 and an imaging optical system having a plurality of lenses. An imaging device comprising the optical filter according to claim 7 and a light receiving element that receives light that has passed through the optical filter. A window material comprising the electrochromic element according to any one of claims 1 to 6 and a transistor connected to the electrochromic element. An electrochromic mirror comprising the electrochromic element according to any one of claims 1 to 6 and a reflective member disposed inside or outside the electrochromic element. 1. A method for producing an electrochromic device having a first electrode, a second electrode, a separator bisecting a gap between the first electrode and the second electrode, a first electrochromic layer disposed between the first electrode and the separator and including at least one electrochromic compound, and a second electrochromic layer disposed between the second electrode and the separator and including at least one electrochromic compound, comprising:
A method for manufacturing an electrochromic element, comprising bonding the first electrode to the separator, and bonding the second electrode to the separator via an acrylic adhesive, curing the acrylic adhesive, and then performing a heat treatment.

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